Adaptive beamforming is a technology in which sounds other than a voice are suppressed by radiating an acoustic beam in a direction in which a user's voice is output.
Conventional noise canceling techniques using a microphone array include a first method using a correlation between signals input to microphones of a microphone array and a second method using an energy ratio between a target signal and a reference signal.
A conventional noise canceling system using a microphone array includes at least one microphone, a short-term analyzer connected to each microphone, an echo canceller, an adaptive beamforming processor that cancels directional noise and turns a filter weight update on or off based on whether or not a front sound exists, a front sound detector that detects a front sound using a correlation between signals of microphones, a post-filtering unit that cancels remaining noise based on whether or not a front sound exists, and an overlap-add processor.
In the conventional noise canceling system and method using the microphone array, an adaptive filter of a Generalized Sidelobe Canceller (GSC) cannot properly adapt when a position of directional noise changes or burst noise having large energy occurs. This is due to a difficulty in tracking variation of noise.
Also, when a noise source has a high autocorrelation, such as a human voice, adaptation performance of the adaptive filter also deteriorates and a noise remains.
The first method using correlation has a problem in that it cannot be used in an actual environment because, when noise of a direction that has to be canceled is colored noise with a high autocorrelation, such as music or a television sound, performance deteriorates.
The second method is not suitable for an actual environment either since performance deteriorates as a signal to noise ratio (SNR) is reduced.